public class Linklist {
      public class ListNode {
      int val;
      ListNode next;
      ListNode() {}
      ListNode(int val) { this.val = val; }
      ListNode(int val, ListNode next) { this.val = val; this.next = next; }
  }
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode cur = new ListNode(0);
        ListNode tem = cur;
        while(list1 != null && list2 != null){
            if(list1.val > list2.val){
                cur.next = list2;
                list2 = list2.next;
                cur = cur.next;
            }else{
                cur.next = list1;
                list1 = list1.next;
                cur = cur.next;
            }
        }
        if(list1 == null) cur.next = list2;
        if(list2 == null) cur.next = list1;
        return tem.next;
    }
}
